Can't type certain brackets anymore

I've always been able to write [,],{ and } using an external keyboard, no problem. Lately, this doesn't work anymore. The problem must be with Carnets, as the keys work perfectly fine everywhere else. I've tried using Carnets plus to solve this, but the situation is the same.

No file, test, device or OS version is provided beyond external-keyboard input in Carnets and Carnets Plus. Start by reproducing [, ], {, and } in both apps, then locate the keyboard-input entry point; done means those four characters work again without breaking other keyboard input.

Written by the indexing model from the issue text.